1. Field of the Invention
This invention relates to a novel additive composition for use in motor fuels. The additive comprises the reaction product obtained by reacting a 4-alkyl-2-morpholinone with a hydrocarbyl oxypolyoxyalkylene amine to produce a motor fuel--soluble amidoalkanolamine compound which provides a number of valuable properties in a motor fuel composition.
The combustion of a hydrocarbon motor fuel in an internal combustion engine leads to the formation and accumulation of deposits on various parts of the combustion chamber as well as on the fuel intake and exhaust system of the engine. The presence of deposits in the combustion chamber seriously reduces the operating efficiency of the engine. First, deposit accumulation within the combustion chamber inhibits heat transfer between the chamber and the engine cooling system. This leads to higher temperatures within the combustion chamber, resulting in increases in the end gas temperature of the incoming charge. Consequently, end gas auto-ignition occurs causing engine knock. In addition, the accumulation of deposits within the combustion chamber reduces the volume of the combustion zone, causing a higher than design compression ratio in the engine. This, in turn, can also lead to engine knocking. A knocking engine does not effectively utilize the energy of combustion. Moreover, a prolonged period of engine knocking can cause stress fatigue and wear in pistons, connecting rods, bearings and cam rods of the engine. The phenomenon noted is characteristic of gasoline powered internal combustion engines. It may be overcome by employing a higher octane gasoline which resists knocking for powering the engine. This need for a higher octane gasoline as mileage accumulates has become known as the engine octane requirement increase (ORI) phenomenon. It is particularly advantageous if engine ORI can be substantially reduced or eliminated by preventing or modifying deposit formation in the combustion chambers of the engine.
Another problem common to internal combustion engines is the formation of intake valve deposits. Intake valve deposits interfere with valve closing and eventually will lead to valve burning. Such deposits interfere with valve motion and valve seating and tend to reduce the volumetric efficiency of the engine and to limit the maximum design power. Valve deposits may be produced from thermally and oxidatively unstable fuel or from lubricating oil oxidation products. The hard carbonaceous deposits produced collect in the tubes and runners that are part of the exhaust gas recirculation (EGR) flow. These deposits are believed to be formed from exhaust particles which are subjected to rapid cooling while mixing with the air-fuel mixture. Reduced EGR flow can result in engine knock and in nitric oxide, NO.sub.x, emission increases. It would therefore be desirable to provide a motor fuel composition which minimizes or overcomes the formation of intake valve deposits.
2. Description of the Prior Art
Various motor fuel compositions and additives for minimizing or overcoming the formation of combustion chamber and intake valve deposits are described in the prior art.
For example, co-pending co-assigned application Ser. No. 07/896,700 filed Jun. 10, 1992 discloses a motor fuel additive composition of the formula: ##STR4## in which R represents a monovalent aliphatic radical having from 1 to 10 carbon atoms; R' represents a hydrocarbyl radical having from 4 to 30 carbon atoms; x has a value of from about 5 to 50; and R" represents a methyl radical or a mixture of hydrogen and methyl radicals.
Co-assigned U.S. Pat. No. 5,203,879, issued on Apr. 20, 1993, discloses a motor fuel additive composition of the formula: ##STR5## in which R represents a monovalent aliphatic radical having from 1 to 10 carbon atoms, R' represents an alkyl, an alicyclic or an alkyl-alicyclic radical having from 12 to 30 carbon atoms; x has a value of from about 5 to 50; and R" represents a methyl radical or a mixture of hydrogen and methyl radicals.
U.S. Pat. No. 4,747,851 discloses a novel polyoxyalkylene diamine compound of the formula: ##STR6## where c has a value from about 5-150, b+d has a value from about 5-150, and a+e has a value from about 2-12. Motor fuel compositions comprising the novel polyoxyalkylene diamine, alone or in combination with a polymer/copolymer additive are also disclosed.
U.S. Pat. No. 4,659,337 discloses the use of the reaction product of maleic anhydride, a polyether polyamide containing oxyethylene and oxypropylene ether moieties, and a hydrocarbyl polyamine in a gasoline motor fuel to reduce engine ORI and provide carburetor detergency.
The use of a mixture of (i) the reaction product of maleic anhydride, a polyether polyamine containing oxyethylene and oxypropylene ether moieties and a hydrocarbyl polyamine, and (ii) a polyolefin polymer/copolymer as an additive in motor fuel compositions to reduce engine ORI is described in U.S. Pat. No. 4,659,336.
U.S. Pat. No. 4,643,738 discloses a motor fuel composition comprising a deposit-control additive which is the reaction product of a dibasic acid anhydride, a polyoxyisopropylene diamine of the formula: ##STR7## where x has a value of 2-50, and an N-alkyl-alkylene diamine.
U.S. Pat. No. 4,631,069 discloses an alcohol-containing motor fuel composition which additionally comprises an anti-wear additive which is the reaction product of a dibasic acid anhydride, a polyoxyisopropylene diamine of the formula: ##STR8## where x has a value of 2-68, and an N-alkyl-alkylene diamine.
U.S. Pat. No. 4,604,103 discloses a motor fuel deposit control additive for use in internal combustion engines which maintains cleanliness of the engine intake system without contributing to combustion chamber deposits or engine ORI. The additive disclosed is a hydrocarbyl polyoxyalkylene polyethylene amine of molecular weight range 300-2,500 having the formula: ##STR9## where R is a hydrocarbyl radical of from 1 to about 30 carbon atoms; R' is selected from methyl and ethyl; x is an integer from 5 to 30, and R" and R'" are independently selected from hydrogen and --(CH.sub.2 CH.sub.2 NH).sub.y --H, where y is an integer from 0 to 5.
U.S. Pat. No. 4,581,040 discloses the use of a reaction product as a deposit-inhibitor additive in fuel compositions. The reaction product is the condensation product of the process comprising (i) reacting a dibasic acid anhydride with a polyoxypropylene diamine of the formula: ##STR10## where x is a numeral of about 2-50, thereby forming a bis-maleamic acid; (ii) reacting said maleamic acid with a polyalkylene polyamine, thereby forming a condensate product; and (iii) recovering said condensate product.
U.S. Pat. No. 4,357,148 discloses a motor fuel additive useful in controlling ORI which is the combination of (a) an oil-soluble aliphatic polyamine containing at least one olefinic polymer chain, and (b) a polymer, copolymer, or corresponding hydrogenated polymer or copolymer of a C.sub.2 -C.sub.6 mono-olefin with a molecular weight of 500-1,500.
U.S. Pat. No. 4,234,321 discloses a hydrocarbyl-poly(oxyalkylene) ureylene carbamate as a deposit control additive for fuels.
EP 297996 discloses an alkylphenylpoly(oxypropylene) aminocarbamate having a molecular weight ranging from 600 to 6000 for use in gasoline or diesel fuel compositions.